1. Field of the Invention
The invention relates to a valve cartridge for a solenoid valve and to an associated solenoid valve.
2. Description of the Prior Art
A conventional solenoid valve, in particular for a hydraulic assembly, which is used for instance in an anti-lock brake system (ABS) or traction control system (TCS) or an electronic stability program system (ESP system), is shown in FIGS. 1 through 5. As can be seen from FIGS. 1 through 5, the conventional solenoid valve 1, which is embodied for instance as a regulating valve that is open when without current, includes a magnet assembly 5 for generating a magnetic flux, which magnet assembly in turn includes a housing jacket 5.1, a winding holder 5.2, a coil winding 5.3, and a cover disk 5.4, and the solenoid valve further includes a valve cartridge 2, which in turn includes a capsule 2.1, a valve insert 8 inserted by a first end into the capsule 2.1, a magnet armature 4 with a tappet 6, and a restoring spring 7. In the production of the conventional solenoid valve 1, the capsule 2.1 and the valve insert 8 of the valve cartridge 2 are joined together by pressing, and the valve cartridge 2 is sealed off hydraulically from the atmosphere by a sealing weld 2.2. In addition, the valve insert 8 absorbs the compressive forces occurring in the hydraulic system and conducts them onward via a calked flange 8.1 to a calked region 41 of a fluid block 40.
By means of current supplied to the coil winding 5.3 via electrical terminals 5.5, the magnet assembly 5 generates a magnetic force that moves the longitudinally movable magnet armature 4, along with the tappet 6 that includes a flat filter 6.1 with a main sealing element 6.2, toward the valve insert 8 counter to the force of the restoring spring 7, and the tappet 6 and restoring spring 7 are guided in an inner bore in the valve insert 8. The valve insert 8 conducts the magnetic flux, introduced by the magnet assembly 5 via the cover disk 5.4, axially in the direction of the magnet armature 4 via an air gap 5.6. Moreover, on a second end, the valve insert 8 receives the so-called valve body 9, which includes a main valve seat 9.1 into which the main sealing element 6.2, embodied as a sealing dome plunges sealingly, in order to perform the function of sealing the solenoid valve 1.
As can also be seen from FIGS. 1 through 5, a lower valve part 10 is placed axially against the valve insert 8 and braced; it includes a check valve 10.1, disposed eccentrically to the main valve axis and having a check valve seat 10.2, and a check valve closing element 10.3. The lower valve part 10, embodied for instance as a plastic insert, additionally serves to seal off from the surrounding fluid block 40, for sealing off from the valve body 9, and for receiving a flat filter 11 with an inserted screen and a recess 11.2 for the check valve 10.1. Moreover, in the solenoid valve 1 shown, an entirely injection-molded ring filter 3 with a support element 3.1 and a filter element 3.2 for filtering out dirt particles is constructed/installed in such a way that associated sealing points 3.3, 3.4 are disposed directly between the ring filter 3 and the solenoid valve 1, in order to avoid bypasses. Via an upper sealing point 3.3, the ring filter 3 seals off axially from the valve insert 8, and via a lower sealing point 3.4, it seals off radially relative to the adjoining component, in this case the lower valve part 10. The plastic flat filter 11 is connected to the adjoining lower valve part 10, in order to ensure the installation and handling of the complete solenoid valve 1 in production. In the solenoid valve construction shown, an annular rib 11.1 of the flat filter 11 plunges into an encompassing annular groove 10.6 of the lower valve part 10. The annular rib 11.1 is partially pressed in the annular groove 10.6 radially to make a captive fastening. These partial press-fittings 10.5 are located in the vicinity of a sealing lip 10.4 of the lower valve part 10. The sealing lip 10.4 has the function of a hydraulic seal in the fluid block 40. By means of the partial press-fittings 10.5 with the flat filter 11, asymmetrical introductions of force into the sealing lip 10.4 can occur, as a result of which the sealing function relative to the fluid block 40 can be impaired. An axial contact area for the flat filter 11 is ensured in the lower valve part 10 by means of a superelevated contour in the form of a C-rib 10.7. In the vicinity of the C-rib 10.7, major accumulations of material occur, and thus major differences in wall thickness in the lower valve part 10. This can lead to flaws (bubbles) and thus to problems of strength in the component. Moreover, the structural height of the solenoid valve and the construction of the lower valve part are affected by this type of connection.